<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    const ary = [{ a: 6 }, { a: 1 }, { a: 5 }, { a: 2 }];
    // filter, map, reduce
    const filter = (array) => {
      let myArr = array.filter((v) => v.a > 1)
      console.log(myArr);
      myArr = myArr.map((v) => v.a.toString())
      console.log(myArr);

      myArr.sort((a, b) => a - b)
      return myArr.reduce((pre, val) => pre + val, '')
    }
    console.log(filter(ary));
  </script>
</body>

</html>